A whole host of internet discussion forums are available as alternatives, some of which have been started by posters who were either banned or left FreeRepublic voluntarily. Other liberty forums focus on libertarian ideology, news and were centered around Congresman Ron Paul's run for the presidency. Here is a partial list: http://www.democraticunderground.com/
Although he did mention democraticunderground, he left off stormfront, they are big on this stuff as well.